Description:

The frequency response strongly depends on size & shape of radiating patch, substrate
material & height of the antenna.The substrate of the proposed antenna is made of FR4
material having relative permittivity (?r) 4.4, which is easily available and cheaper in cost.
Mathematical equation (1) & (2) given below has been applied on isosceles triangular
radiating patch having 15mm, 15mm and 10mm sides with 70.529°, 70.529° and 38.942°
angles to get the primary resonant frequency (dominant mode TM10) of the antenna, which
has been calculated to be as 5.22GHz.
f
? ?
? (1)
2 2 2
? i ? ? i ? k m n (2)
Where,
fr=Resonant frequency
k=Eigen value
m,n=numbers to represent modes of resonant frequency
c=3x1010cm/sec,a & ß having the usual definitions
After getting 5.22 GHz calculated resonant frequency, HFSS ver.13 software has been used to design and analyse the conventional isosceles triangular antenna, in order to find the optimum probe position and bandwidth of primary resonant band. For finding optimum probe position, first the probe has been placed at the base on the median of the triangular patch along y-axis and analysed the result. After that the probe shifted 1mm above on median and again analysed the results, in this way the probe shifted 1mm step size from base to top corner on y-axis of the triangular patch and analysed the results of each probe position. After analyzing the results of all probe position, the position 3mm from base has been found optimum probe position.S11 of each probe position has been shown in fig.2.
Fig.2 Graph showing S11for different probe position on the median from base till the top corner of the triangular radiating patch.
At the optimum probe position 3mm from base over median, resonant frequency is 5.34GHz, with minimum S11 of -22.5dB as shown in fig. 3 below. Also, Simulated surface current distribution at 5.34GHz without slot, Equivalent circuit model of initial antenna design and Comparison of S11 of Equivalent Circuit model with S11 of HFSS has shown in fig.3.
Fig.3 (a) Design of initial antenna with optimum probe (3mm on the median from base) position. (b) S11 of antenna at optimum probe position.(c)Simulated surface current distribution at 5.34GHz without slot (d)Equivalent circuit model of initial antenna design(e) Comparison of S11 of Equivalent Circuit model with S11 of HFSS.
After that the conventional isosceles triangular radiating patch has been slotted with an I-slot of optimum size and position to lower the resonant frequency band of the antenna, so that it can occupy the desired application bands.

Claims:

1) Smallest Isosceles Triangular Microstrip Patch Antenna for WLAN application comprising of 2) isosceles triangular radiating patch, 3) an I shaped slot on the radiating patch, 4) an FR4 substrate separating the radiating patch and the ground plane, 5) a finite size copper ground plane, 6) a 50 O SMA connector to feed the antenna.
2) Smallest Isosceles Triangular Microstrip Patch Antenna for WLAN application as claimed in claim 1 utilizing a isosceles triangular radiating patch made of copper. Side lengths of the triangle are 15mm, 15mm and 10 mm.
3) Smallest Isosceles Triangular Microstrip Patch Antenna for WLAN application as claimed in claim 1 with an ‘I’ shaped slot of dimension (3mm X 1 mm) on the radiating patch.
4) Smallest Isosceles Triangular Microstrip Patch Antenna for WLAN application as claimed in claim 1 with an FR4 substrate of permittivity 4.4 (loss tangent of 0.02) with a thickness of 3.2 mm. 5) Smallest Isosceles Triangular Microstrip Patch Antenna for WLAN application as claimed in claim 1 with a finite size ground plane made of copper. Dimension of the ground plane is (30 mm X 34 mm).
6) Smallest Isosceles Triangular Microstrip Patch Antenna for WLAN application as claimed in claim 1 with a 50 O SMA connector. ,